This invention generally relates to liners for containers, more particularly to flexible liners that closely conform to the full perimeter of the inside walls of self-supporting containers. Such conforming liner includes a plurality of conforming seals each having a length substantially the same as the height of the vertical walls of the container, each conforming seal being spaced laterally from an edge of the liner. When the liner is installed within the container, each edge of the liner remains between the liner and the container, and each conforming seal defines a corner that is adapted to closely overlie and engage a vertical corner of the self-supporting container.
Utilization of flexible liners for providing readily releasable surfaces along the inside panels of free-standing containers has been well-known for many years. Included is the use of open-mouth polymeric film liners or bags for providing a continuous inner surface for boxes of various products, including chemicals, foods and other products, wherein the liner provides a layer of material along the inside surface of the container, box or the like. A particular application along these lines is in connection with cheese-making operations. Many cheese products are made within large containers, generally known as "Tosca boxes" which are designed to provide a bulk cheese-making container to make a block of cheese weight approximately 640 pounds.
Generally speaking, a Tosca box type of container is a four-sided wooden or metal sleeve. With cheesecloth enclosing the bottom of this structure, cheese curd is poured into the box, and the whey is pressed from the curd and through the cheesecloth. The open top of the box or container is then closed with a suitable lid, and the thus closed container is stored or shipped for further processing and/or packaging. After the cheese has set for the desired length of time, the walls of the container or box are separated from each other and from the cheese that has set therewithin. At this stage, it is important that the walls of the container or box be flat and adequately releasable from the set cheese so that the cheese block will have sides that are relatively smooth and undamaged. Traditionally, such releasability had been provided by waxing the inside walls of the container or box, but this procedure is quite labor intensive. In more recent years, the wax has been replaced by a flexible film liner.
Widely used flexible film liners in this regard take the form of cylindrical film sleeves or tubes that generally line the inside surface of the container or box. These types of sleeve liners have a height that is somewhat greater than the height of the container or box, whereby the sleeve is folded over a mouth-defining peripheral edge of the container and over a portion of an outside surface of the container in order to form a liner cuff or overlap that is several inches in length and that assists in holding the liner in place. Usually, this cuff arrangement is provided on both the top periphery and the bottom periphery of the container or box.
The principal difficulty with these generally cylindrical sleeve or tube liners is that, in order to provide enough film to permit liner fold over and cuff formation, the perimeter of the sleeve is greater than the inside perimeter of the container or box. As a result, in the case of cheese making, before the cheese curd is poured into the box, the worker must carefully fold the liner so that its excess perimetrical film material will lie flat against the inside surface of the box while, and hopefully after, the cheese curd is filled into the container or box. This is exceedingly difficult to accomplish due to the flexibility of the liner material and the shifting thereof that occurs while the curd is poured into the box and up against the liner. If, as is all too often the case with these types of liners, the cheese curd flows into pockets formed in the liner by the excess perimetrical film material, the set cheese will likewise form within these pockets. When the liner is removed for subsequent processing, cutting and/or packaging of its cheese block, a portion of the cheese block at or in the vicinity of these pockets often breaks away thereby losing cheese weight and damaging the appearance of the cheese block and reducing the total yield of commercially acceptable product that is obtained from each block when it is cut into smaller blocks.
One advantage of these prior art liners is that they are relatively inexpensive because of their substantially simple construction. Inexpensiveness is an important attribute and necessary feature of these types of liners inasmuch as they are not reused and are looked upon as a disposable item that cannot be particularly elaborate or expensive to manufacture.
An improvement upon these cylindrical film sleeves or tubes is represented by my U.S. Pat. No. 4,558,801 which discloses a conforming liner having a conforming seal area. Conforming liners of this type have significant advantages over the liners which preceded it. Experience with the conforming liners specifically described in U.S. Pat. No. 4,558,801 has indicated these liners do not conform to the full perimeter of the box in many applications. For example, the liner can be spaced away from the box, especially in corner areas, and undesirable bunching or folding over of the liner has been experienced along the areas between the corners.
In addition, the so-called Tosca boxes are being replaced by more modern containers. For example, in the cheese-making industry so-called Arena boxes have come into use. These are boxes of molded polymer panels that have a somewhat waffle-like texture. Boxes of this type include those available from A.R.Arena Products, Inc., which have walls containing horizontal and vertical spaced ribs that define open spaces so as to reduce the weight of the box while enhancing the rigidity. Plastic panel boxes of this style have panel walls that are substantially thicker than those used in the past. For example, a wooden-walled Tosca box typically is made of three-quarter inch plywood. More recently used stainless steel boxes have wall thicknesses on the order of three-quarters of an inch to one inch. Waffle-walled plastic boxes such as Arena boxes have a wall thickness of at least about one and one-quarter inch. The thicker-walled boxes increase the difficulty of having the liner conform as closely as possible to the inside surface of the box because of the need in all boxes to have a cuff portion that folds over the open end of the box to properly hold the liner in place. Thicker box walls require the cuff to fold over a greater length, thereby complicating the design of the liner so as to accommodate this longer cuff span.
Accordingly, there is a need for an inexpensive liner that is easily installed and maintained in position within a container or box, even when the container or box is of the thicker-walled variety and when it is being filled with a flowable material such as cheese curd and the like. Such needs are satisfied by the present invention which provides a liner having an inside surface that closely conforms to the full perimeter of the container or box being lined while still providing a mouth-defining portion having a periphery that is oversized to permit the formation of a cuff portion for folding over the lip of the box.
These desirable features and advantages are accomplished according to the present invention by providing a conforming liner that is a sleeve-like member having a cuff portion periphery which is greater than the periphery of the inside of the container or box to be lined and which conforming liner further includes at least four conforming seal areas that combine to define a sleeve-like member that emulates the shape and size of the full periphery of the inside of the container or box. Each conforming seal area is spaced from an edge of the cuff portion periphery and has a length which is substantially the same as the height of the container or box being lined.
It is accordingly a general object of the present invention to provide an improved liner for a container or box.
Another object of this invention is to provide an improved liner that closely conforms to the inside dimensions of the full perimeter of a container or box while including an extraordinarily sized peripheral edge portion that readily forms a cuff which overlies the peripheral edge of the container or box.
Another object of the present invention is to provide a full perimeter conforming liner that is inexpensive and that requires minimal effort to install and to maintain in place during filling of a box or container within which it is inserted.
Another object of the present invention is to provide an improved full perimeter conforming liner wherein the liner includes at least four sections of excess material which is maintained behind an inside surface of the conforming liner that lies flush along the inside surface of the container or box.